1. Field of the Invention
The present invention relates to pattern forming apparatuses and pattern forming methods, movable body drive systems and movable body drive methods, exposure apparatuses and exposure methods, and device manufacturing methods, and more particularly to a pattern forming apparatus and a pattern forming method that are suitable for being used in a lithography process when manufacturing electron devices such as semiconductor devices and liquid crystal display devices, a movable body drive system, a movable body drive method, an exposure apparatus and an exposure method that can suitably be used when manufacturing the electron devices, and a device manufacturing method in which the exposure apparatus, the exposure method or the pattern forming method is used.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing electron devices (microdevices) such as semiconductor devices (integrated circuits or the like) or liquid crystal display devices, exposure apparatuses such as a reduction projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner)) are mainly used.
In these types of exposure apparatuses, the wavelength of used exposure light is getting shorter year by year due to finer integration circuit, and also the numerical aperture of a projection optical system is gradually getting larger (larger NA), to improve the resolution. However, there has been a possibility that the focus margin at the time of exposure operation becomes insufficient because a depth of focus becomes too narrow due to the shorter wavelength of exposure light and the larger NA of the projection optical system. Therefore, as a method of substantially shortening an exposure light wavelength and also increasing (widening) a depth of focus compared in the air, an exposure apparatus making use of a liquid immersion method has been gathering attention recently (e.g. refer to the pamphlet of International Publication No. 2004/053955).
Further, as the requirement for overlay accuracy becomes stricter to cope with finer integrated circuits, improvement in position controllability (including position setting performance) of a stage (wafer stage) on which an object to be exposed, for example, a wafer or a glass plate (hereinafter, generally referred to as a ‘wafer’) is mounted has been also required. Therefore, in the recent exposure apparatuses, the wafer stage has been downsized so as to be a slightly lager than the wafer, and another stage (which is also called a measurement stage), which mounts various types of measuring instruments that were mounted on the wafer stage before, such as a sensor that receives illumination light via the projection optical system (such as an illuminance monitor or an irregular illuminance sensor that receives illumination light on an image plane of the projection optical system, and an aerial image measuring instrument that measures light intensity of an aerial image (projected image) of a pattern that is projected by the projection optical system, which is disclosed in, for example, Kokai (Japanese Unexamined Patent Application Publication) No. 2002-014005) and the like), has been arranged separately from the wafer stage (e.g. refer to the pamphlet of International Publication No. 2005/074014). In an exposure apparatus that is equipped with the measurement stage, various types of measurement can be performed using the measurement stage, for example, in parallel with wafer replacement on the wafer stage, and as a consequence, the throughput can also be improved. Further, in this exposure apparatus, for example, a best focus position of the projection optical system is measured using the aerial image measuring instrument, and based on the measurement result, focus leveling control of the wafer stage (wafer) on exposure is performed.
In this case, however, a stage used for measuring the best focus position and a stage used for the focus leveling control of the wafer on exposure are different, and therefore focus leveling control error could occur on exposure, and thus, exposure defect could occur due to defocus.
Further, position measurement of the wafer stage is generally performed using a laser interferometer with a high resolution. However, position control of the stage with higher precision has been required due to finer patterns to cope with semiconductor devices with higher integration, and therefore, short-term fluctuation of measurement values of the laser interferometer which is caused by temperature fluctuations of the atmosphere on the beam path is becoming unignorable now.